Dataset: phostree.dat

Source: C. Johannessen (1958). "Higher Phosphate values in Soils Under Trees
Than in Soils Under Grass," Ecology, Vol. 39, #2, pp. 373-374.

Description: Phosphate values (ppm of PO4) at 7 elevations: under grass, under
pines, and under oaks. Treated as paired differences (trees versus grass,
separately for pines and oaks).

Variables/Columns
Elevation   1-8
PO4 under grass  12-16
PO4 under pines   20-24
PO4 under oaks   28-32